1. Field of the Invention
This invention relates to an endoscope to be inserted into a region of interest of a human subject and, in particular, to an endoscope having at a distal end portion a solid-state image sensor to which shielding wires are connected as a signal cable.
2. Description of the Prior Art
A conventional endoscope is disclosed, for example, in Japanese Patent Disclosure (KOKAI) Nos. 55-54933 and 58-69528. This endoscope includes an image sensor unit equipped with a solid-state image sensor as an observation means to which shielding wires are connected in the form of a signal cable. In this case, the forward ends of the shielding wires are electrically connected to the lead-in terminals or a substrate of the solid-state image sensor.
When the endoscope is inserted into a region of interest of a human subject, the insertion section of the endoscope is bent and thus a protective tube containing a cable is also curved, with the result that the cable, interconnection between the cable and the substrate, and/or interconnection between the cable and the lead-in terminals of the solid-state image sensor undergo an external force. This may involve a risk of the associated components being separated from the corresponding interconnection areas.
In the neighborhood of the solid-state image sensor of the conventional endoscope, an amplifier is usually provided to amplify a signal from the solid-state image sensor. Where, however, the solid-state image sensor and associated amplifier are not adequately shielded, they are liable to suffer an external noise. Particularly where an electrical device, such as a high-frequency treatment device, is employed together with this endoscope, a noise emerges on the screen of a monitor, failing to adequately observe the region of interest of a human subject.